The present invention relates to an electronic switch circuit which can selectively provide any one of three or more outputs in accordance with a specific level of one input.
NTSC system and CCIR system are assigned to the architecture of a video tape recording/reproducing system (hereinafter referred to as "VTR" system). In addition, the beta format of NTSC system contains a .beta.II mode being adapted to a standard tape transporting speed and a .beta.III mode being adapted to a low tape transporting speed for a long recording time. Accordingly, in a VTR system being applicable to those three modes(.beta.II, .beta.III and CCIR), it is necessary to change the operation mode of the an internal circuit of VTR according to the kind of VTR architecture and to the tape transporting speed. Where such an internal circuit of the VTR is made of a semiconductor integrated circuit(hereinafter referred to as "IC"), the IC package requires two exclusive external terminals (pins). One of the terminals is used for designating the kind of architecture(NTSC or CCIR), and the other is used for selecting the tape transporting speed (.beta.II of .beta.III).
Generally speaking, the number of external pins of the IC should be as small as possible because a large number of IC pins enlarges the size of IC package. A large sized IC inevitably invites substantial disadvantages: increase of a unit cost of an IC, difficulty in a compact design of electronic circuit block, etc. Further, in general, the number of external pins of IC is standardized as seen in a dual in-line type mold package. When a switch circuit for selecting one of said three modes (.beta.II, .beta.III and CCIR) is practically designed, according to prior art, two input pins for the mode selection are necessary.